Specifications

Diamond™ GEM, G, & K, Integrator’s Guide

BEAM DELIVERY

Many difficulties in laser processing systems arise from deficiencies

in the beam delivery system. The beam delivery system has the vital

job of transmitting the initially high-quality beam emitted by the

laser to the workpiece without having the beam degraded by

misalignment or aberrations. In addition, the beam delivery system

must protect itself and the laser from light reflected from the

processing region. In almost all environments, the beam delivery

system must be enclosed and purged to protect the optics from

contamination by dirt.

Alignment

When designing a laser system, provision must be made for align-

ment of all the optical components. When a component moves, the

beam alignment must be maintained throughout the excursion of

that component. This, in general, requires that one of the elements

on the moving beam path must be adjustable in both translation and

angle. Most beam bending modules have adjustments for angular

alignment, but need to be mounted on slotted carriers or slides to

allow for translation. The visible alignment laser (optional on the

Basic package and standard on the Performance package of K-series

lasers) makes alignment of a complex beam delivery system much

quicker and easier than aligning with the CO

beam. The visible

alignment laser should only be used for approximate alignment. It is

not the same wavelength as the CO

beam so some errors in beam

positions could occur.

A detailed alignment procedure, as well as all necessary targets,

should be supplied with every laser system.

Sealing

It is critically important to keep all of the optics in a high-power CO

laser system clean. Dirt on an optic does far more than reduce the

beam quality; it damages, usually permanently, the optical surface

itself. Particulate materials are heated quite strongly by the beam and

conduct this heat to the surface on which they sit. The coating under

the particle is destroyed by this heat. Cleaning the optic may remove

the particle, but the damage remains.

Industrial lasers often work in relatively dirty surroundings. In many

cases, the laser process itself contributes to local airborne contami-

nation. The only way to preserve the laser and beam delivery optics